The most important discovery of the twentieth century in fish farming was the method of hormonal stimulation, which made it possible to obtain mature germ cells in artificial conditions in almost all fish species. The first works on the use of pituitary tissue homogenates for the induction of ovulation were carried out in Brazil [30–32]; however, bringing the method to industrial use is associated with the name of the Leningrad ichthyologist Nikolai Gerbilsky. The first publications of Gerbilsky N.L. on hormonal stimulation were made in 1937‐1938 [11; 12; 17], and in 1938 the Laboratory of the Basics of Fish Farming was established to introduce and improve the method of pituitary injections. Working with pituitary specimens Gerbilsky N.L. started out on bony fish, one of the species used was the Neva smelt Osmerus eperlanus, from sturgeon the first object of research was the stellate sturgeon Acipenser stellatus.
One of the most important technical problems the new laboratory faced was to develop a method for the mass collection of sturgeon pituitary glands, in which the cartilaginous skull and brain are covered from above by very hard integumentary bones. Initially, the operation was performed by cutting off the upper overhead bones of the skull with a sharp knife, and then the pituitary gland was removed with a curved spear (used by dentists) and rubbed between two watch glasses with a few drops of saline until a thin suspension was obtained. For injection, Lumbar or Bier needles were used, which were inserted directly into the skull from a thick layer of the cartilaginous tissue of the skull. The injected fish were kept in the river on a kukan [11; 12].
To facilitate the process of extracting the pituitary glands, special trepans were made (Fig. 1a, b). The art of the fish breeder was to precisely determine the location and direction of drilling the skull of sturgeon fish. It was important not to step aside so as not to damage the pituitary gland. It was especially difficult to get the pituitary gland from the large beluga Huso. Later, trepans began to be supplied with braces, which made it possible to reduce the time for drilling the cartilaginous plug.